Essilor International (compagnie Generale D'optique)

Ocular Sciences, Inc.

Richard Legras

Nicolas Chateau

Bruno Fermigier

Dominique Baude

Toric contact or intraocular lenses having a correcting portion characterized by one or more novel constructions that each produce an optical path that improves angular misalignment tolerance. The lens may be constructed with a &ldquo;smooth atoric&rdquo; aspect where the optical path through the correcting portion of the lens corrects for both astigmatism and an axisymmetric aberration other than astigmatism, there being no sudden surface discontinuity between the regions that provide the different corrections (thus, &ldquo;smooth&rdquo;). In another embodiment, the lens may be constructed with so-called &ldquo;sectors&rdquo; circumferentially arranged around the optical axis such that an optical path through the correcting portion of the lens varies as a function of the angular separation from the reference meridian plane, and the correcting portion is divided into at least two sectors having different astigmatism correction axes. In either embodiment, the correcting surface may be provided on either or both of the anterior or posterior faces of the lens, and the optical performance of the lens in case of angular displacement (the &ldquo;angular misalignment tolerance&rdquo;) is increased. Specifically, the angular misalignment tolerance is increased by at least 30% over a standard toric lens of the same class. Definition of the particular shape of the lens enables a mold die of that shape to be formed, or lens machining tools may be used.

Contact or intraocular lens and method for its preparation

In a method of producing tolerance markings on a contact lens for correcting astigmatism which has a given cylinder, the tolerance markings comprise at least two straight line segments in the peripheral part of the contact lens with an angle 2.alpha..sub.T between them. The angle 2.alpha..sub.T between the two straight line segments of the tolerance markings depends on the cylinder of the contact lens.

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Robinson, France

Richard Legras